In Microsoft Purview, the Data Catalog stores the metadata of the data assets (SQL tables, data files etc.) that were scanned. If an asset (e.g. a table) is deleted from the data source (e.g. Azure SQL Db), that asset remains in the Purview until a follow up scan is performed later.
Question: How can we keep those data assets in Purview that were deleted from the corresponding data source.
Remark: Please note that data assets in purview are not the actual data asset but only the metadata of that asset. And we want to keep that meta data information. For example, if TableA is dropped from the Azure SQL db after the db was purview scanned, we don't want its corresponding data asset (also named TableA) to be removed from Purview in the next purview scan.
If you do that you are using the data catalog for the wrong purpose. The whole point of a data catalog is to know exactly what data you have. It is not an approximation of the data you have but shows 1-1 metadata about the data you have. It is a search tool to access metadata (meaning documentation) about the actual data in the organisation. So it would be a wrong use of a data catalog to keep outdated metadata information in it.
If you want to keep the information it should be because you have a data source that has a specific purpose for the business, and is used by the business. This data's metadata is then scanned into the data catalog.
In addition, keeping data without a specified purpose can depending on the data be illegal in parts of the world. For example in the EU.